﻿Shader "Fractal/Mandelbrot" {
	Properties {
		_MainTex ("Albedo (RGB)", 2D) = "white" {}
		_Zoom ("Zoom", Vector) = (1,1,1,1)
		_Pan ("Pan", Vector) = (0,0,0,0)
		_Aspect ("Aspect Ratio", Float) = 1
		_Iterations ("Iterations", Range(1,256)) = 128
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200
		
		CGPROGRAM
		// Physically based Standard lighting model, and enable shadows on all light types
		#pragma surface surf Standard fullforwardshadows

		// Use shader model 3.0 target, to get nicer looking lighting
		#pragma target 3.0

		sampler2D _MainTex;

		struct Input {
			float2 uv_MainTex;
		};

		float4 _Zoom;
		float4 _Pan;
		float _Iterations;
		float _Aspect;

		void surf (Input IN, inout SurfaceOutputStandard o) {
			// Albedo comes from a texture tinted by color
			//fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;

			float2 c = (IN.uv_MainTex - 0.5) * _Zoom.xy * float2(1, _Aspect) - _Pan.xy;
			float2 v = 0;
			float m = 0;
			const float r = 5;

			for (int n = 0; n < _Iterations; ++n) {
				v = float2(v.x * v.x - v.y * v.y, v.x * v.y * 2) + c;

				if (dot(v, v) < (r * r - 1))
				{
					m++;
				}

				v = clamp(v, -r, r);
			}

			float4 color;
			if (m == floor(_Iterations)) {
				color = float4(0,0,0,1);
			} else {
				color = float4(sin(m / 4), sin(m / 5), sin(m / 7), 1) / 4 + 0.75;
			}

			o.Albedo = color;
			//o.Emission = color;
			// Metallic and smoothness come from slider variables
			o.Alpha = color.a;
		}
		ENDCG
	}
	FallBack "Diffuse"
}
